When performing optical analysis on specimens, it is customary to discard the specimen after the optical analysis. For rare cells, however, it is often desirable to preserve the specimen for further testing or for use in further procedures. In certain procedures, it is desirable to select a specimen from a relatively small sample, in the order of 10-100 ml, and it is likely that the volume of the specimen which may be extracted from such a small sample is limited, making it especially important to avoid destruction of the specimen or any substantial part thereof. It is likewise important to avoid contamination of the specimen and to avoid conditions which would lead to deterioration of the specimen or impairment of the analysis.
One cause of specimen deterioration is exposure of the specimen to air bubbles which may not only cause deterioration of the specimen but the presence of bubbles may adversely affect the optical analysis of the specimen.
Numerous devices are available for containing a specimen for analysis, but there has been no collection chamber which is designed to isolate a small sample for analysis and to preserve the sample for additional testing. Specifically, there has been no collection device which enables the exclusion of air in the form of bubbles or in other forms from the sample chamber.
For example, U.S. Pat. No. 5,246,669 discloses a sampling device for collecting a small sample and mixing it with a test liquid. In this patent, the device provides a pickup device which extracts a small sample from a larger quantity of solid or semi-solid material to be tested. The device separates the small sample from the residue and isolates the residue so as to avoid contamination of the small sample or the surrounding atmosphere. The device does not provide for salvaging either of the test sample or the residue and does not have any provision for excluding air in the form of bubbles from the test liquid.